(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Text Book Of Mechanical Engineering"

loS

Forging Spanners.

cotter E           little description.    It may be formed by bending

a thin strip of Iron as at F, welding the portion near the bend, and
chipping out the narrow shank.

The student will have already noticed that a good deal of
Judgment has to be exercised by the smith in deciding upon the
length and breadth of iron necessary to execute a certain piece of
work, and. although this can rarely be achieved with very great
nicely, yet practice enables him to guess it with sufficient accuracy.
As a role the cubic contents, or the weight of the stuff should he
about the same in the rough as in the finished piece, some
allowance being made for burning away In the fire, but it is best
to err by having rather too much tban too little, and in most
articles the extra stuff can very easily be cut off. Some, however,
require more exact measurement, as from the nature of their con-
struction the after cutting cannot well be resorted to. Wherever
parts have to be afterwards machined extra material should be
allowed, say from one-sixteenth to one-eighth of an inch, but the
careful smith will always leave as little as possible, and if he is
directed to finish *&lack3 he should make the work as exact to
dimension as his tools will allow.

Except in the case of the nut at Fig. 105, none of the work
already described has called for the operation of welding. We
shall now, however, pass on to some examples requiring the aid
of this Important process,

A common S or Double-sEnded Spanner is the article
we shall first consider. A, Pig. in, shews the finished forging.
A bar Is taken of the same length as the arm, leaving a little
extra material for welding. It is heated and first bent to the S
form (B) on the anvil beak, straightening by flat hammering on
the face of the anvil; -and is next drawn out at the ends as at c.
Now, two pieces of rather thicker bar being procured to form
the jaws, these are heated and bent round the beak, and the
comers chipped off and rounded as at r>. Heating again, these

are finished on the bottom tool and scarfed down as shewn
at ?, We are now ready to complete the 'spanner by welding the
Jaws to the arm, at the searings already made (see &), and finish

be given between the flat face H, and the anvil..
In Fig. na, A represents a Shackle for use with chain or